Water bodies can be polluted by a wide variety of substances, including pathogenic microorganisms, putrescine organic waste, fertilizers and plant nutrients, toxic chemicals, sediments, heat, petroleum , and radioactive substances. Not only does this spell disaster for aquatic ecosystems, the pollutants also seep through and reach the groundwater, which might end up in our households as contaminated water we use in our daily activities, including drinking.

Some of water pollutions are caused by direct sources, such as factories, refineries, etc, that directly release waste and dangerous by-products into the nearest water resource without treating them. Indirect sources include pollutants that infuse in the water bodies via groundwater or soil or via the atmosphere through acid rain. 

Some of the sources of water pollution are-

• Domestic Waste- Groundwater is one of our least visible but most visible but most critical natural resources. With rainfall it becomes groundwater as it seeps to the earth filling up the cracks, crevices and porous aquifers which is an underground store house of water. Drinking water gets polluted when contaminants such as fertilizers, pesticides and water leaching from separate systems make their way into the system. It becomes polluted and unsafe for humans and remains unusable for decades or even thousands of years. 
• Industrial Effluents-  Industries produce tremendous amount of waste which contains toxic Chemicals and pollutants causing air pollution and damages our environment. They contain harmful Chemicals including lead, Mercury, sulphur, nitrates, asbestos, etc. The toxic Chemicals may change the colour of water, increase the number of minerals , lead to eutrophication and change the temperature of water.
• Insecticides and pesticides- These are washed off into water sources and pose a threat to the the quality of the water. 

• Acid rain- It is essentially water pollution caused by air pollution. When the acidic particles released in the atmosphere by thr pollution mix with water vapour, it results in acid rain.
• Sewage and Wastewater- A small leakage from the sewer line can completely contaminate the underground water and make it imperfect for the people to drink. Also when not repaired on time, the water can come onto the surface and become a breeding ground for insects.
• Marine Dumping- 80% of Ocean pollution or marine pollution originates onland along the coast or far inland. Streams and rivers contains Chemicals nutrients and heavy metals that are carried from farms, factories and cities into the bays, in estuaries and from there the into the oceans.                  Water pollution also leads to many diseases such as typhoid, Cholera, Hepatitis and many others. It results in eradication of ecosystem, eutrophication and severe impact on the food chain.                             The best way to prevent large scale water pollution is to reduce its wastage. There are numerous small changes we can make to protect ourselves from a future where water is scarce.                                                                Life is ultimately about choices and so is water pollution. We cannot live with sewage- strewn beaches, contaminated rivers, and fish that are poisonous to eat and drink. To avoid these scenarios, we can work together to keep the environment clean so the water bodies, plants, animals, and people who depend on it remain healthy. We can take action as countries and continents to make a safe and healthy future.                                                       

  

Sources:- 

https://Britannica.com/science/water-pollution

https://wwf.panda.org/discover/knowledge_hub/teacher_resources/webfieldtrips/water_pollution/